Sound reproducing apparatus



July 9, 1935. R. E. TOLERTON 2,007,484

SOUND REPRODUCING APPARATUS Filed April 6, 1954 Jag/.1. F 0.2. 2

[NVENTOR A T TORNE K Patented July 9, 1935 UNITED STATES PATENT OFFICE SOUND REPRODUCING APPARATUS Ray E. Tolerton, Fort Wayne, Ind., assignor to The Magnavox Company, Fort Wayne, Ind., a corporation of Arizona Application April 6, 1934, Serial No. 719,320

8 Claims. (01. 179-1155) The present invention relates to electrodynamic one upon which the coil ends can be effectively sound reproducing apparatus, and more particsecured without threading the fine coil forming ularly to an improved diaphragm coil and supwire through perfora ions in the C Supp t port and method of forming same. member.

i Apparatus of this character usually employs Another object of the invention is to provide a 5 a diaphragm in the form of a truncated cone, il supp rting m m r for a diaphragm actuto the small end of which there is attached an ating coil which will have no greater radial thickactuating coil. This actuating coil operates in ness than that necessitated by the material forman annular magnetic air gap which, for maxig e upp member a d the layers of Wire 10 mum efiiciency, must have a flux path that is as wound thereupon. 10 short as possible. Therefore, it is necessary that A further object of the invention is to provide the diaphragm actuating coil and its support be a novel method of temporarily securing the ends constructed with a minimum radial thickness. It of the coil upon the coil supp member is also desirable that the diaphragm coil and its ing and after the winding operation.

support be of light construction so as not to With the above and other objects in view, the 15 greatly increase the mass and consequently the invention resides in the construction, combinainertia of the diaphragm assembly. Considerable tion and a ra m t o parts substantially as difiiculty has been experienced in making 9, diawill be hereinafter described and more particuphragm actuating coil supporting member which larly defined by the appended claims.

would have a minimum thickness and weight and For a better understanding of the invention 20 at the same time suflicient strength to withstand reference should be had to the accompa y the necessary handling, incident to the winding drawing wherein there is shown, y W y Of u and assembly operations. tration and not of limitation, a preferred embodi- Heretofore, a coil support has been formed of ment thereof.

a short length of fibre tubing having a peripheral In the drawing; 25 groove cut at one end, into which the coil could Figure 1 is an enlarged view of one side of a be wound. In a later development, the coil sup- 0011 Suppo member u t d n a cordport was made entirely of paper wrapped in the ance with this invention, form of a tube with additional layers of narrow Figure 2 is an enlarged view of the other side strips of paper wound thereupon in spaced relaof the coil supporting member illustrated in Fig- 0 tion to form coil positioning flanges. These lir w th a p t n broken a y, and having a structures were heavy, expensive to manufacture coil wound thereupon,

and objectionable because of the thickness neces- Figure 3 shows a method of attaching the coil sary forstrength. supporting member to a diaphragm of the type In United States Patent Number 1,891,404 to having an inside coil centering spider, and 35 Bernard A. Engholm, there is shown a coil sup- Figure 4 shows a method of attaching the coil port formed of a single thin strip of paper which upportin member a diaphragm 0f the type is embossed so as to provide a cylinder having having an outside centering spider. upstanding ridges for positioning the coil there- As shown in Figures 1 a d 2 0 the drawing,

40 upon. In this construction full advantage is the coil supporting member, designated by the 40 taken of the reduction in thickness, thus pronumeral I 0,is provided with a raised or embossed vided, by threading the ends of the coil through portion l I at its outer end, and embossed portions perforations and bringing them out toward the I2 which are disposed in spaced relation with the diaphragm across an interior recess formed by embossed portion H, so as to define a circumthe embossing operation. While this construcferentially extending coil positioning recess I 3. 45 tion results in a coil and support assembly having The embossed portions l2 extend outwardly from a minimum radial thickness, it involves the tedithe coil positioning recess l3 along and about the ous and time consuming operation of threading coil supporting member ill, so as to form oppothe fine, hair like, coil forming wire through the sitely extending helical grooves l4 into which ends small openings provided in the support and consel5, of a coil 16, may be diSpOSed after he Coil 50 quently is expensive and difficult to manufacture. has been wound. In addition to the embossed In order to overcome the above disadvantages, portions II and I2, the coil suppo member D it is an object of this invention to provide a coil is shown as having its opposite end enlarged in supporting member, upon which the coil may be diameter to provide a diaphragm engaging surwound in a simple and convenient manner, and face 11. a

supporting member, as shown in the drawing' After the coil supporting member it has been formed in the die it is provided with three notches l8, which are located centrally with respect to the helical grooves l4, and also a pair of spaced notches 19 located in alignment with the outer ends of each of the helical grooves M. The coil supporting member ,EB, formed and notched as above, can now be slipped upon a suitable mandrel and wound with: the required number of turns of wire to form the coil l6. At the commencement of the winding operation'one end E of the coil forming wire may be secured to the end of the coil supporting'member 59 by cinching it in one of the pairs of notches i9.

' wound helically along the support in the correspending helical groove l ito the coil positioning recess I3 where the coil is wound. After the coil 55 has been fully wound, preferably with two or an even number of layers of wire, the other end oflthe coil forming wire is brought outalong'the remaining helical groove i i across the previously secured end E5 of the wire and to the other pair of notches I9 where it is cinched to thus secure the coil'ends.

From the above, it will be seen that the wire forming the coil It can be wound and secured upon the coil supporting member Win a simple and convenient manner without requiring any extra wire securing accessory or athreading of the coil ends through perforations in the coil supporting member. 1' e After the coil supporting memberit; has been wound and'taken from the mandril it is coated or dipped, up to the point where the ends l5 of the coil H5- cross, in a suitable hard dryingplastic, such as a thin varnish or the like, and allowed to dry. A drying of the varnish or other plastic coil H5 are uncros sed, at the point wherethetwo helical grooves M meet, and carried along in spaced relation to the notches :awhere they are secured,,as shown in Figures 3 and l of the draw ing. l

When the coil l 6 has been wound upon the coil supporting member ID and its ends secured thereto, asoutlined above, it is ready for mounting upon a diaphragm. V

In-Figure 3 of the drawing, the coil supporting member i8 is shown asmounted upon a conical diaphragm 25 which is supported at its small end by meansof a so-called insidecentering spider 2!. The inside centering spiderZi is shown as glued at its periphery in an annular groove 22 formed on the inside surface of the diaphragm 20. At its small end the diaphragm 20 has a cylindrical flange 2-3 which is adapted to be glued to'the diaphragin engaging surface ll of the coil supporting member Hi. When the cylindrical fiange'23 This wire is then' is slipped over the end of the coil supporting member it, the free ends l5 of the coil forming wire will be carried down under the flange 23 and brought up over the outside .thereof to fixed terminals 26 which are secured to the outside of the diaphragm 2B. The ends it? of the coil l6 are then connected to an external circuit by means of flexible leads 2-5 which are attached to the terminals 24.

In Figure 4 of the drawing, the coil supporting member 50 is shown as mounted upon a conical diaphragm 26 which is supported at its small end by a so-called outside centering spider 21. In this arrangement the coil supporting member ID is secured. to the'diaphragm 23 in the manner pre-' viously described and the outside centering spider 21, which has an annular flange 28, is then slipped over the outside of a flanged portion 29 upon the diaphragm 25 and there secured by a suitable adhesive. Theoutside centering spider El" carries terminals 38, to which the'coil ends l5 can be soldered, and flexible leads 3!, for connecting the coil E6 to an external circuit, extend outwardly from theterminals 30.

A forming. of the coil supporting member It! in ..ie manner described above has the advantage that it is possible to bring out the coil ends 15 without increasing the over all radial thickness of the coil assembly and at the same time secure the ends of the coil during the winding and dipping operations in a simple and convenient manner. Another advantage obtained by the construction described is that after the coil supporting member iii, with its coil it, has been dipped and secured to the diaphragm the free ends 1'5 of the 'coil will be firmly and permanently held in spaced relation by the overlying flange of the diaphragm.

From the above it will be seen that by carry ing: the ends of the coil helically along the support the tension provided in the coil turns during the winding operation can be maintained in a simple and effective manner without requiring any abrupt bending of the coil forming wire, adjacent the'coil positioning groove, which might become displaced and release one or more of the end turns of the coil.

While I have, for the sake of clearness' and in order to disclose my invention so that the same can be readily understood, described and illustrated specific devices and arrangements, I desire to have itunderstood that this invention. is not limited to the specific means disclosed but may be embodied in other ways that will suggest themselves, in view of this disclosure, to persons skilled in the art. It is believed that this invention is new and it is desired to, claim it as such so that all changes as come within the scope of the appended claims are to be considered as part of this invention. I

Having thus described my invention, what I claim and desire to secure by Letters Patent is l. A coil support for electrodynamic apparatus, comprising a substantially cylindrical member having means defining a. coil positioning recess at one end thereof, and having two helical grooves extending from said recess along the outer surface of said cylindrical member and toward its other end into which the coil ends may be disposed. a

2. A coil support for electrodynamic apparatus, comprising a substantially cylindrical member having means defining a coil positioning recess 'and helically disposed grooves extending from said recess and along said cylindrical member toward its other end into which the coil ends may be disposed.

3. A coil support for electrodynamic apparatus, comprising a substantially cylindrical member having a coil positioning shoulder thereupon, helically disposed grooves extending through said shoulder and along said cylindrical member into which the coil ends may bedisposed, and means at the end oi said cylindrical member in line with said grooves to which the coil ends may be secured during the assembly operation.

4. A coil support for electrodynamic apparatus, comprising a substantially cylindrical member having a coil positioning shoulder embossed thereupon, helically disposed parallel ribs extending from said shoulder and along said cylindrical member forming grooves therebetween into which the coil ends may be disposed, and means at the end of said cylindrical member in line with said grooves to which the coil ends may be secured during the assembly operation.

5. A coil unit for electrodynamic apparatus, comprising a substantially cylindrical member having a coil positioning recess at one end thereof, a diaphragm engaging portion at the other end thereof, and having two grooves which originate at the coil positioning recess and extend helically in opposite directions along and around the cylindrical member to the diaphragm engaging portion, a winding in said coil positioning recess having its ends extending in opposite directions in said grooves, and means at the end of said cylindrical member to Which the ends of said winding are secured.

6. A coil unit for electrodynamic apparatus, comprising a substantially cylindrical member having a coil positioning recess at one end thereof, a diaphragm engaging portion at the other end thereof, and having two grooves which originate at the coil positioning recess and extend helically in opposite directions around the cylindrical member to the diaphragm engaging portion, and a winding in said coil positioning recess having its ends disposed in said grooves, said winding and its ends being secured in said coil positioning recess and said grooves by a. plastic coating baked thereon after the winding operation.

7. A diaphragm coil supporting form, comprising a substantially cylindrical member of relatively thin construction having an outwardly extending shoulder embossed thereupon for locating a winding at one end thereof, a plurality of lielically disposed ridges forming grooves into which the end wires of a coil may be disposed, and means in line with said grooves to which the ends of said winding may be secured during and after the winding operation.

8. An actuating coil unit for electrodynamic sound reproducing apparatus, comprising a cylindricai coil supporting member having one end adapted to be secured to a diaphragm and support a coil in spaced relation therewith, a coil wound upon the other end of said coil supporting memher, the ends of the wire forming said coil being brought out and wound spirally in opposite directions about said coil supporting member to a point adjacent its diaphragm engaging end to reinforce said coil supporting member between its coil and diaphragm engaging end, said coil and the spirally wound ends of the wire forming said coil being secured upon said coil supporting member by a hard drying plastic.

RAY E. TOLERTON. 

